King Louis XIII of France is thrilled to have born to him a son - an heir to the throne. But when the queen delivers a twin, Cardinal Richelieu sees the second son as a potential for revolution, and has him sent off to Spain to be raised in secret to ensure a peaceful future for France. - IMDB Description
This film is "transitional", between silent films and "talkies": the film was shot as a silent, and then the sound track (which included narration, music, and sound effects) was added post-production and in several re-releases. There are also two speaking clips that were spliced in.